# [Numpy-discussion] np.seterr doesn't work for masked array?

Chao YUE chaoyuejoy at gmail.com
Fri Dec 14 08:57:30 EST 2012

```Dear all,

I tried to capture the zero divide error when I divide a masked array by
another. It seems that np.seterr is not working for masked array?
when I do np.divide on two masked array, it directly put the zero divides
part as being masked. The np.seterr works if the two arrays for dividing
could anyone explain? thanks!!

np.__version__ = 1.6.2

In [87]: np.seterr(all='print')
Out[87]: {'divide': 'print', 'invalid': 'print', 'over': 'print', 'under':
'print'}

In [88]: a = np.arange(8,dtype=float).reshape(2,4)

In [90]: b[1,-2:] = 0.

In [91]: b
Out[91]:
[[-- -- -- --]
[4.0 5.0 0.0 0.0]],
[[ True  True  True  True]
[False False False False]],
fill_value = 1e+20)

In [92]: c = a.copy()

In [93]: c[1,-2:] = 0.

In [94]: c
Out[94]:
array([[ 0.,  1.,  2.,  3.],
[ 4.,  5.,  0.,  0.]])

In [95]: np.divide(a,b)
Warning: divide by zero encountered in divide
Out[95]:
[[-- -- -- --]
[1.0 1.0 -- --]],
[[ True  True  True  True]
[False False  True  True]],
fill_value = 1e+20)

In [96]: np.divide(a,c)
Warning: divide by zero encountered in divide
Out[96]:
array([[ nan,   1.,   1.,   1.],
[  1.,   1.,  inf,  inf]])

Chao
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Chao YUE
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